TRT is an upper respiratory tract infection of turkeys that is caused by pneumovirus. It is a highly contagious, acute disease that afflicts turkeys of all ages. The clinical symptoms of TRT infection include a marked, frequently frothy nasal discharge, rales, snicking, sneezing, and head shaking. Ocular discharge or swollen infraorbital sinuses may also be observed in infected turkeys.
Antibodies to TRT virus (TRTV) have been detected in some chicken flocks (both broilers and broilers/breeders) suffering from Swollen Head Syndrome (SHS). It is postulated that TRTV plays a role in the etiology of SHS and related respiratory distress.
Commercially-available vaccines for TRT are not administered in ovo. Rather, they are administered post-hatch in a variety of formats. Typically, such vaccines are administered by the labor-intensive methods of spraying (e.g., hand spray, knapsack spray, or automated-spray equipment) or in drops (eye or nose).
As more fully explained below, the in ovo administration methods of using TRT vaccines modified for in ovo use provides distinctive advantages over the inconvenient and time-consuming post-hatch routes of administration presently available.